Despite increases in obesity among infants and toddlers, few published interventions promoting healthy diet and decreased sedentary behaviors among this age group exist. To fill this gap, we propose a randomized controlled trial among 468 Non-Hispanic black women, their families, and their child caregivers to test the efficacy of a multi-component, tailored intervention versus an attention control (child safety) in promoting healthy weight gain patterns during infancy. The proposed intervention, Mothers and Others: Family-based Obesity Prevention for Infants and Toddlers will be one of the first to meet the unique needs of individual families by delivering anticipatory guidance on infant care, feeding and growth through multiple channels and to multiple caregivers. Primary modes of delivery for the intervention arm will include face-to-face counseling through 9 home visits (1 by a certified Lactation Consultant), 6 tailored health newsletters for mothers and 6 targeted health newsletters for other caregivers deemed influential by mothers, as well as ~160 cue-based text messages for mothers and other caregivers. The control group will receive messages on child safety delivered through general newsletters and text messages. Our main outcome is infant/toddler growth, captured by mean weight-for-length z-scores (WLZ) at 18 months, mean change in WLZ between 0-18 months, and likelihood of overweight (WLZ e 95th percentile) at 18 months. Differences between groups are expected to be achieved through uptake of targeted health behaviors, including a greater likelihood of breastfeeding initiation, exclusivity and duration; after 6 months, higher dietary intakes of whole fruits and vegetables and lower intakes of energy-dense snack foods; longer durations of infant and toddler sleep and fewer night awakenings; and, lower levels of television and electronic media exposure. We further hypothesize that these targeted health behaviors will be achieved through modifiable risk factors underpinning the intervention, namely more positive breastfeeding attitudes; higher levels of parenting and breastfeeding self-efficacy; higher levels of perceived social support; higher responsive feeding style scores; improved accuracy in perceiving infant/toddler weight status; and, diminished parental perceptions of infant fussiness. We believe Mothers and Others is highly significant and innovative, as it targets a minority population at high risk of early life obesity, it begins during pregnancy, a teachable moment for establishing healthy behaviors, it actively engages multiple child caregivers, and it utilizes novel intervention platforms, including tailoring and text messaging. We have assembled a strong, interdisciplinary team of researchers, each with an outstanding record for implementing and publishing research relevant to this intervention. Collectively, we have experience conducting similar interventions in this population; designing, implementing and evaluating the proposed tailoring and novel technology components; recruiting and retaining a similar cohort; and measuring and analyzing relationships between the proposed modifiable risk factors, targeted health behaviors and outcomes of early life growth. PUBLIC HEALTH RELEVANCE: Family-based Obesity Prevention for Infants and Toddlers is an efficacy trial of a multi-component, tailored intervention focused on infants of Non-Hispanic Black mothers and families, a minority population at high risk for pediatric obesity. Mothers and Others contains several innovations, including beginning during a 'teachable' moment, pregnancy; use of color-coded growth charts to enhance caregiver recognition of child growth and size; active engagement of multiple caregivers ('mothers and others'); and the use of tailoring and novel media technologies. If successful in promoting healthy infant growth and enhancing caregiver health behaviors, Mothers and Others will have high public health relevance for future obesity-prevention efforts aimed at children less than two years, including intervention research studies and federal, state and community health programs.